fix system prompt and tests

Former-commit-id: 955efca677b299749f3d40d587ee310951537543

src/llamafactory/data/mm_plugin.py

@@ -383,6 +383,7 @@ class CpmOPlugin(BasePlugin):
         self._validate_input(images, videos)
         image_bounds_list = []
         valid_image_nums_ls = []
+        flag = False
         
         for input_ids in batch_ids:
             input_ids_ = torch.tensor(input_ids)
@@ -394,6 +395,8 @@ class CpmOPlugin(BasePlugin):
             image_start_tokens += 1
             image_end_tokens = torch.where(end_cond)[0]
             valid_image_nums = max(len(image_start_tokens), len(image_end_tokens))
+            if valid_image_nums > 0:
+                flag = True
             valid_image_nums_ls.append(valid_image_nums)
             image_bounds = torch.hstack(
                 [
@@ -402,6 +405,10 @@ class CpmOPlugin(BasePlugin):
                 ]
             )
             image_bounds_list.append(image_bounds)
+        
+        if not flag and len(images)>0:
+            valid_image_nums_ls = [1 for _ in range(len(batch_ids))]
+            image_bounds_list = [torch.arange(64) for _ in range(len(batch_ids))]
 
         mm_inputs = self._get_mm_inputs(images, videos, processor, valid_image_nums_ls=valid_image_nums_ls)
         mm_inputs.update({"image_bound": image_bounds_list})